This application requests support to establish a NRSA Postdoctoral Training Program in Substance Abuse Prevention Research within the Division of Prevention and Community Research and The Consultation Center, Department of Psychiatry, Yale University School of Medicine. A combination of didactic, mentored, and independent research experiences over a two-year period will prepare future prevention scientists for careers as independent investigators with expertise in the development, implementation, and rigorous evaluation of science-based substance abuse prevention research. The program will emphasize three fundamental areas of learning. First, the major theoretical focus of the training program will be the conceptualization, design, and implementation of research within an ecological framework. Second, trainees will learn that prevention science involves a process of knowledge development and application that moves through certain phases - a pre-intervention phase (problem analyses using epidemiological and risk/protective factor research), an intervention phase (in which change strategies involving universal, selective, or indicated designs are chosen that are most likely to modify identified risk and protective factors and then implemented through the conduct of efficacy and effectiveness trials), and a diffusion or going-to-scale phase (in which effective interventions are disseminated on a broad basis, implementation fidelity is monitored, and dissemination efforts are evaluated). A major emphasis of this aspect of the program will be to address two significant knowledge gaps in the field;1) between tightly controlled efficacy studies and their replication as effectiveness studies in real-world contexts;and 2) between successful effectiveness trials and their diffusion. The third fundamental area of learning will focus on research methodologies. Training will include state-of-the- art quantitative research methods and data analytic approaches, especially for the analysis of longitudinal research designs. In addition, extensive training will be provided on the ethical conduct of research.